“On Saturday mornings, children gather to paint and draw in the main downtown shopping street of Curitiba, in southern Brazil. More than just a charming tradition, the child’s play commemorates a key victory in a hard-fought, ongoing war. Back in 1972, the new mayor of the city, an architect and urban planner named Jaime Lerner, ordered a lightning transformation of six blocks of the street into a pedestrian zone. The change was recommended in a master plan for the city that was approved six years earlier, but fierce objections from the downtown merchants blocked its implementation. Lerner instructed his secretary of public works to institute the change quickly and asked how long it would take. “He said he needed four months,” Lerner recalled recently. “I said, ‘Forty-eight hours.’ He said, ‘You’re crazy.’ I said, ‘Yes, I’m crazy, but do it in 48 hours.’ ” The municipal authorities were able to accomplish it in three days, beginning on a Friday night and installing paving, lighting, planters and furniture by the end of the day on Monday. “Being a very weak mayor, if I start to do it and take too long, everyone could stop it through a juridical demand,” Lerner went on to explain. “If they stop the work, it’s finished. I had to do it very fast, at least in part. Because we had discussed it a great deal. Sometimes they have to have a demonstration effect.” . . . ”